Fuel Injector 129100-53100 YM129100-53100 for Komatsu 3D75-2 3D78-1 3D82AE-3 3D84-2 4D84E-3 4D84-2 4D88E-3 Yanmar 3TN75E 3TN82E 4TN82E 4TNE98 Engine

Fuel Injector 129100-53100 YM129100-53100 for Komatsu 3D75-2 3D78-1 3D82AE-3 3D84-2 4D84E-3 4D84-2 4D88E-3 Yanmar 3TN75E 3TN82E 4TN82E 4TNE98 Engine

This fuel injector is engineered as a direct replacement for the Komatsu 3D75-2 3D78-1 3D82AE-3 3D84-2 4D84E-3 4D84-2 4D88E-3 Yanmar 3TN75E 3TN82E 4TN82E 4TNE98 Engine. Manufactured to meet or exceed OEM specifications, it delivers reliable performance in demanding conditions. Each unit is tested for fuel flow, pressure rating, and durability before leaving the factory to ensure consistent quality across every order.

Vehicle Compatibility

Replaces OEM Part Numbers

129100-53100 • YM129100-53100 • YM12910053100 • 12910053100 • Komatsu • Engine • 3D75-2C • 3D75-2D • 3D75N-1YC • 3D75N-2E • 3D78-1A • 3D78-1C

Signs You Need a Replacement

If your equipment is showing any of these symptoms, the injectors & nozzle may be the cause:

• Rough idle or misfire — Uneven fuel delivery from a worn injector causes the engine to shake at idle. On Komatsu engines, this is often accompanied by a knocking sound under load.
• Black or white exhaust smoke — Black smoke means excess fuel; white smoke indicates incomplete combustion. Both point to injector spray pattern degradation.
• Loss of engine power — A single failing injector reduces cylinder output. Multi-cylinder engines lose noticeable power when one injector flows less than the rest.
• Increased fuel consumption — Poor atomization means the engine burns more fuel to produce the same power. Monitor your fuel burn rate as an early warning sign.
• Hard starting or no start — If the injector doesn’t deliver fuel on cranking, the cylinder won’t fire. This is especially common in cold weather with worn nozzles.
• Fuel in engine oil (dilution) — Fuel leaking past the injector seat seal contaminates the crankcase oil. If the oil level rises or smells of diesel, inspect the injectors immediately.

Replace as a Set

Replace all injectors as a set whenever possible. On Komatsu engines, mixing old and new injectors creates uneven fuel delivery — the new injectors compensate for the worn ones, shortening their life. When installing, use new copper sealing washers and torque to the specification in the service manual. After installation, run the engine at idle for 5 minutes to bleed air from the fuel system, then check for leaks at each injector connection before putting the machine under load.

Frequently Asked Questions

Which Komatsu models does this part fit?
Refer to the Vehicle Compatibility table above for the full list of Komatsu models. Each listing includes the body type, engine, and production years. Match your vehicle’s engine code (stamped on the engine block) against the listed codes to confirm.

Can I cross-reference 129100-53100 with YM129100-53100?
Yes. Both 129100-53100 and YM129100-53100 are interchangeable OEM numbers for this part. They refer to the same component with the same specifications, just different part number revisions.

How do I check if my engine code (PC20R, PC27R, PC35R, PC45R) matches?
The engine code is stamped on a metal tag attached to the engine block, usually near the timing belt cover or on the cylinder head. Compare the code you find with the list above. Engine codes are 3 to 6 characters long.

My vehicle is a 9100 model – is it covered?
The compatibility range for this part includes 9100-5310. The 9100 model year falls within this range, but verify the engine code and body type match. Mid-year production changes sometimes mean two vehicles from the same model year use different parts.

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